Preheat oven to 350 degrees. Spray a muffin tin with non stick spray. I prefer this method rather than using liners. The muffins tend to stick to the liners and they come out smoothly when just using non stick spray.
Combine all streusel ingredients in a bowl. Mix with two forks or your fingers until you reach a crumb/sandy consistency. Set aside.
In a separate, large bowl combine the flour, sugar, baking powder, cinnamon, salt, and nutmeg. Set aside.
In a separate bowl, whisk together milk, egg, butter, and vanilla. Pour the wet ingredients over the dry ingredients and gently stir until combined. You do not want to over mix.
Place a spoonful (about 1 tablespoon) of the muffin mix in each prepared muffin cup. Top with 1 tablespoon of streusel mix. Top with another spoonful (about 1 tablespoon) of muffin mix. Top with remaining streusel.
Bake muffins for 18-20 minutes or until a toothpick inserted in the center comes out clean. Enjoy!